Experimental Study on the Acoustic Emission Characteristics of Fully-graded Concrete Under Static and Dynamic Loading

摘要

Experimental study on the acoustic emission (AE) characteristics of three fully-graded concrete specimens under static and dynamic third-point flexural loading is carried out. The AE characteristics, such as the amplitude, energy, ring counts and hits of the specimens are studied to analyze the damage process and mechanism of the fully-graded concrete. The results of specimen under static loading show that there are only some interfacial cracks at 40% of the ultimate load and the interfacial cracks extend to the mortars when the load is between 40% and 80% of the ultimate load. A few of the coarse aggregates rupture when the load is larger than 80 percent of the ultimate load. The amounts of the hits and counts increase greatly and there is penetration crack when the specimen fractures. The similar study on the specimen under dynamic loading indicates that the typical Kaiser phenomenon occurred. The curve of energy vs. time indicates that under dynamic cycle loading the cracks close in the intermission of loading cycles. In the first loading cycle the interfacial and mortal cracks appear at 1/3 of the ultimate load. The coarse aggregates begin to rupture at 80% of the ultimate load and rupture at every peak load. The difference of specimens under static and dynamic loading is also presented. The results show that AE technique is useful to study the damage mechanism of fully-graded concrete under seismic loading.